This invention is generally directed to toner and developer compositions, and more specifically the present invention is directed to toner compositions, including magnetic, single component, and colored toner compositions. In one embodiment of the present invention, the toner compositions are comprised of resin particles, certain magnetite particles, a charge enhancing additive, a wax component, and external additives, such as colloidal silicas like Aerosil R972.RTM. or Aerosil R812.RTM., available from Degussa Chemical. Furthermore, in another embodiment of the present invention there are provided single component toner compositions comprised of resin particles, certain magnetic components such as silane treated magnetites like Toda MAT305K3, a (3-chloropropyl)trimethoxysilane treated magnetite, obtained from Toda Kogyo Corporation of Japan, alkylene waxes like polypropylene, and polyethylene with a low molecular weight, for example from about 500 to about 20,000, and preferably with an average molecular weight of about 4,000, and available from Sanyo Corporation of Japan, charge control additives, and as external surface additives metal salts of fatty acids, colloidal silicas, or mixtures thereof. The toner compositions of the present invention are useful in electrostatographic imaging systems, especially xerographic imaging and printing systems wherein the toner is substantially insensitive to relative humidity, and enables developed images with excellent optical density.
Developer and toner compositions with certain waxes therein are known. For example, there are illustrated in U.K. Patent Publication 1,442,835, the disclosure of which is totally incorporated herein by reference, toner compositions containing resin particles, and polyalkylene compounds, such as polyethylene and polypropylene of a molecular weight of from about 1,500 to 6,000, reference page 3, lines 97 to 119, which compositions prevent toner offsetting in electrostatic imaging processes. Additionally, the '835 publication discloses the addition of paraffin waxes together with, or without a metal salt of a fatty acid, reference page 2, lines 55 to 58. In addition, many patents disclose the use of metal salts of fatty acids for incorporation into toner compositions, such as U.S. Pat. No. 3,655,374. Also, it is known that the aforementioned toner compositions with metal salts of fatty acids can be selected for electrostatic imaging methods wherein blade cleaning of the photoreceptor is accomplished, reference Palmeriti et al. U.S. Pat. No. 3,635,704, the disclosure of which is totally incorporated herein by reference. Additionally, there are illustrated in U.S. Pat. No. 3,983,045 three component developer compositions comprising toner particles, a friction reducing material, and a finely divided nonsmearable abrasive material, reference column 4, beginning at line 31. Examples of friction reducing materials include saturated or unsaturated, substituted or unsubstituted, fatty acids preferably of from 8 to 35 carbon atoms, or metal salts of such fatty acids; fatty alcohols corresponding to said acids; mono and polyhydric alcohol esters of said acids and corresponding amides; polyethylene glycols and methoxy-polyethylene glycols; terephthalic acids; and the like, reference column 7, lines 13 to 43.
Described in U.S. Pat. No. 4,367,275 are methods of preventing offsetting of electrostatic images of the toner composition to the fuser roll, which toner subsequently offsets to supporting substrates such as papers wherein there are selected toner compositions containing specific external lubricants including various waxes, see column 5, lines 32 to 45.
Of background interest are U.S. Pat. Nos. 3,165,420; 3,236,776; 4,145,300; 4,271,249; 4,556,624; 4,557,991 and 4,604,338.
Moreover, toner and developer compositions containing charge enhancing additives, especially additives which impart a positive charge to the toner resin, are well known. Thus, for example, there is described in U.S. Pat. No. 3,893,935 the use of certain quaternary ammonium salts as charge control agents for electrostatic toner compositions. There are also described in U.S. Pat. No. 2,986,521 reversal developer compositions comprised of toner resin particles coated with finely divided colloidal silica. According to the disclosure of this patent, the development of images on negatively charged surfaces is accomplished by applying a developer composition having a positively charged triboelectric relationship with respect to the colloidal silica. Further, there is illustrated in U.S. Pat. No. 4,338,390, the disclosure of which is totally incorporated herein by reference, developer and toner compositions having incorporated therein as charge enhancing additives organic sulfate and sulfonate compositions; and in U.S. Pat. No. 4,298,672, the disclosure of which is totally incorporated herein by reference, positively charged toner compositions containing resin particles and pigment particles, and as a charge enhancing additive alkyl pyridinium compounds, inclusive of cetyl pyridinium chloride. Toner compositions with certain negative charge enhancing additives are also known. Further toners with magnetites, such as Mapico Black, are known. The aforementioned Mapico Black toners have a number of disadvantages with certain resin particles, for example they are sensitive to relative humidity, and this and other disadvantages are avoided, or substantially prevented with the toners and processes of the present invention. Other prior art disclosing positively charged toner compositions with charge enhancing additives include U.S. Pat. Nos. 3,944,493; 4,007,293; 4,079,014 and 4,394,430.
Toner compositions with negative charge enhancing additives, such as TRH, available as Spilon Black, reference for example U.S. Pat. No. 4,333,040, the disclosure of which is totally incorporated herein by reference, are also known. Moreover, toner compositions with a vinyl monomer obtained by polymerizing said monomer in the presence of a titanate coupling agent, and at least one inorganic material, such as magentite, is disclosed in U.S. Pat. No. 4,600,676. With the invention of the present application wherein there is selected a magnetite treated with a silane coupling, a number of advantages are achievable as compared to toners with the aforementioned titanate treated magnetite, such as a higher optical density at various relative humidities, such as above 60 percent.
Although the above described toner and developer compositions are useful for their intended purposes, there is a need for improved compositions. More specifically, there is a need for toner compositions, including single component compositions which possess advantages not achievable with similar prior art toner compositions. There is also a need for toner compositions with reduced humidity sensitivity, no, or minimal offsetting of toner, and wherein developed images with optical densities of 1.2 to 1.5 result. Also, there is a need for single component toners wherein the developed images thereof are of excellent resolution, and no significant background or variation of optical density on the paper substrate results.